Sentinel-3A satellite flying over land and oceans
Sentinel-3A is the third satellite in the family of Copernicus satellites.
Copernicus programme is headed by the European Commission (EC) in partnership
with the European Space Agency (ESA).
Sentinel-3A satellite was launched on February 16th 2016 from Russia to its sun synchronous orbit, more than 800kms above our heads, with the amazing mission of monitoring our mother earth and oceans health.
Five instruments have been integrated on board, including the Ocean and Land Colour Instrument (OLCI), a spectrometer based on a custom HORIBA Jobin Yvon (HJY) concave diffraction grating.
The mission is based on two identical satellites orbiting in constellation to optimize the global coverage and data delivery. The second satellite Sentinel-3B will be launched in 2017 and is also integrated the same OLCI instrument containing the same high grade HJY grating.
The mission is the result of a close collaboration between ESA and CNES space agencies along with a hundred of industries among which we may cite THALES ALENIA SPACE as the global leader of the satellite project SODERN in charge of the spectrometer manufacturing, and of course HORIBA JOBIN YVON to supply the challenging diffraction gratings.
“This is the third of the Sentinel satellites launched in the less than two years – and it is certainly a special moment. It also marks a new era for the Copernicus Services, with Sentinel-3 providing a whole range of new data with unprecedented coverage of the oceans,” said the Director of ESA’s Earth Observation Programmes, Volker Liebig.
The OLCI instrument is a medium-resolution imaging spectrometer, based on heritage from Envisat’s* spectrometer. The key optical component of this spectrograph is the concave holographic grating manufactured by HORIBA Jobin Yvon, with a groove density close to 130 gr/mm and dimensions of 70*46mm working on the VIS-NIR spectral range. Thanks to the holographic recording and space-qualified (TRL 9) replication process, these gratings exhibited an optimized efficiency level on the spectral range of interest, a low stray light and no ghost.
OLCI features 21 distinct bands in the 400-1020 nm spectral region tuned to specific ocean colour, vegetation and atmospheric correction measurement requirements. Thanks to its 5 cameras this instrument offers a spatial resolution of 300m for all measurements and a swath width of 1270 km to provide a global coverage of the entire earth globe every two days. OLCI’s new eyes on Earth will monitor ocean ecosystems, support agriculture and provide data of atmospheric aerosol and clouds – all of which bring significant societal benefits in many application fields.
Over oceans, it will measure the temperature, colour and height of the sea surface as well as the thickness of sea ice. These measurements will be used, for example, to monitor changes in Earth’s climate or in water pollution.
Over land, this innovative mission will monitor vegetation health, detect forests wildfires and measure the height of rivers and lakes.
More generally, all of these data which are completely available for any user worldwide, will be also used to help in weather forecasting.
The satellite has already delivered impressive first images thanks to its OLCI instrument.
Pictures from OLCI instrument with HJY grating
Copyright : Copernicus Sentinel data (2016)
Left : Morocco’s dry desert, snow-covered peaks of the Atlas Mountains and greener vegetated northern areas of Spain.
Middle : The very first image from the Copernicus Sentinel-3A was taken by the OLCI instrument and shows the transition from day to night over Svalbard, Norway.
Right : Two weeks after launch, this is one of the first images from Sentinel-3A featuring California, Arizona and Mexico.
Following this successful Sentinel A/B projects, HORIBA Jobin Yvon have been chosen again to supply the next batch of space qualified diffraction gratings for the Sentinel C/D futures missions.